The invention relates to a cerclage pin arrangement.
For the stabilization of a bone fraction by means of a straight or rounded trochanter plate cerclage pins are used. Round or long holes are provided in the plate, in which the cerclage pins can be inserted. In the heads of the cerclage pins throughholes are provided in crosswise arrangement, which may house cerclage bands and/or cerclage wires, forming loops around the bone area which is to be stabilized.
Such a cerclage pin arrangement is known from German utility model No. 20,214,220. With this known solution, which does not make use of bone screws, the fixation of the bone is based exclusively on the looping effect of the cerclage bands or wires.
From the U.S. Pat. No. 5,607,430 an implantable bone plate with integrated wire clamps is known, by means of which small distanced plates are provided in rail arrangement on the bone, these small plates having bores in a single direction, by means of which the cerclage wires through and around the bone are fixated. The bone rail cannot be fastened without these plates. Also no additional use of bone screws is possible. Furthermore the use is relatively time-consuming, whereby the danger exists that the small plates on the rail arrangement do not find sufficient hold for a reliable fixation.
A considerable disadvantage in all these known arrangements is that no prefixation exists, i.e. the plates rest unstably on the bone before the cerclage bands or wires are sufficiently fixed, in order to fix the plate securely. Therefore inadvertent shifts or changes of the position of the plate may occur.
From the U.S. Pat. Nos. 5,810,824 and 6,520,965 holding means for cerclage wires are known, which can be only used with bone screws. It is further known that they can take only thin cerclage wires, which effect high pressure loads on the bone. On the other hand additional bone screws are always necessary for the fixation, which for their safe fixation need an appropriate bone area according to the type of fracture. The technical solutions represented in the mentioned US-patents are thus only of limited use.